Add gunicorn component.

component/gunicorn/buildout.cfg

+[buildout]
+
+extends =
+  ../libevent/buildout.cfg
+
+parts = gunicorn
+
+[libevent-linked-egg]
+recipe = zc.recipe.egg:custom
+include-dirs =
+  ${libevent:location}/include/
+library-dirs =
+  ${libevent:location}/lib/
+rpath =
+  ${libevent:location}/lib/
+
+[greenlet]
+<= libevent-linked-egg
+eggs = greenlet
+
+[eventlet]
+<= libevent-linked-egg
+eggs = eventlet
+
+[gevent]
+<= libevent-linked-egg
+eggs = gevent
+
+[gunicorn]
+recipe = zc.recipe.egg
+eggs =
+  ${greenlet:eggs}
+  ${eventlet:eggs}
+  ${gevent:eggs}
+  gunicorn
+dependent-scripts = true